Recent data from the National Health and Nutrition Examination Survey (NHANES) conducted by the National Center for Health Statistics (NCHS) of the CDC reveals that multivitamin, vitamin D and omega-3 supplements are the most popular among all the available options. About half of the adult population takes at least one supplement. It is easy to understand why these products are so popular; people have a legitimate desire for good health, and the supplement industry has a strong desire for good sales. The Dietary Supplement Health and Education Act restricts the FDA's ability to regulate products that are marketed as dietary supplements, even though most people buy them for health reasons, not nutrition reasons.
Manufacturers can sell these products without providing proof of their purity, potency, safety, or effectiveness. To determine if supplements can help, researchers compare the health status of people who take a particular supplement with the health of people who don't in observational studies. However, these results are not always maintained, so randomized clinical trials are conducted in which volunteers are assigned by lot to take the supplement or a placebo (dummy pill) while researchers track their health status. Unfortunately, in most cases, studies have not been able to confirm our hopes, although there are exceptions.
Many people take supplements with the belief that they will preserve health or prevent diseases; many others use supplements in an attempt to treat specific conditions that have already developed. We'll look at popular supplements in both categories. To get vitamin D the old fashioned way, by producing it in the skin, we need a lot of sunlight. However, as work moved from farm to office and we learned to use sunscreens to reduce the risk of skin cancer and wrinkles, many people lack sufficient amounts of the vitamin from the sun.
Older adults, patients with chronic diseases, and people of color are at special risk. Vitamin D is needed to absorb calcium from the intestines, which is why vitamin D is so important for bone health. Current guidelines call for 600 IU (international units) a day before age 71 and 800 IU a day thereafter; however, many experts recommend 800 to 1000 IU a day for most adults; daily doses of up to 4000 IU are considered safe, but more can be toxic. It's very difficult to get the vitamin D you need from your diet; oily fish and fortified dairy products are the only important sources.
Therefore, supplements make sense for most adults. The form known as vitamin D3 is generally recommended, but vitamin D2 is also effective; for best results, take vitamin D with a meal that contains some fat. If you want to make sure you need this supplement, request a blood test; levels of at least 30 nanograms per milliliter are considered the best. Vitamin E, vitamin A, beta-carotene, and vitamin C were favorites of the 1980s and early 1990s.
However, many careful randomized clinical trials have not demonstrated any benefit against heart disease, cancer or other diseases. In fact, even moderately high doses of vitamin A increase the risk of hip fractures; high levels of vitamin A have been linked to an increased risk of prostate cancer; beta-carotene increases the risk of lung cancer in smokers; and vitamin E increases the risk of prostate cancer and has been linked to an increase in respiratory infections, heart failure and overall mortality rate. Vitamin B12 is found only in animal foods so strict vegetarians may need supplements. In addition, many older people don't produce enough of the stomach acid needed to release vitamin B12 from animal products so that they can absorb it.
However, vitamin B12 is also added to fortified cereals and other foods and this synthetic vitamin B12 is easy to absorb even without stomach acid. That means that a single bowl of cereal can provide you with your recommended daily dose of 2.4 micrograms (mcg) per day. However if your intake of fortified grains is irregular a B12 supplement is reasonable. Folate fortification has alleviated the problem of birth defects but obstetricians continue to recommend supplements to women who are trying to conceive or who are already pregnant.
Without questioning these conclusions many doctors have continued to recommend (and take) multivitamins. One reason is that they are a convenient and affordable way to obtain vitamin D but most preparations provide only 400 IU much less than the 800 to 1000 IU currently used. Most people benefit from vitamin D many from fiber and some from fish oil. Unfortunately popular supplements that are used to treat medical problems don't work any better until (or unless) better oversight is available supplements are likely to remain the Wild West of American health.
Today only a few are likely to help some can do more harm than good and most will be nothing more than costly disappointments. However false hopes can be toxic in and of themselves if they prevent you from taking good care of yourself or getting the medical care you need. So even if you take supplements be sure to eat well exercise regularly and work with your doctor to keep your cholesterol blood pressure and blood sugar under control. Also while you're seeing your doctor for checkups screenings and treatments be sure to tell him about all your supplements.